There are many situations where there is a need to securely connect elements such as tubes, pipes, rods, shafts and other elements, including the use of fasteners. Current devices/mechanisms are dependant on the application of sufficient force to reliably connect the elements. In addition in use many items are subject to vibration which increases the likelihood of failure.
Failure can be catastrophic in industrial situations where pipes separate or leakage of high pressure gases or liquids occurs. In addition there are many situations where maintenance and inspection is difficult, expensive, or impossible and it would be a considerable advantage to improve the reliability of connection devices. The use of devices to define locking forces is an extra expense. It would be much better if the devices were inherently more tolerant to vibration misalignment and the stresses that exist.
Further there are many instances where an adjustment can be required between two two elements. For example, the game of golf has its own challenges in connection devices in that golfers are of all ages, strengths, abilities, and physiques, which together significantly influence the dynamics of the golfers swing and subsequent ball impact. Therefore golf clubs would be better if they were able to be tailored more easily to suit this variation. To do this a convenient but reliable adjustment connection device is needed.
Golfing is becoming more prevalent among junior golfers, children between approximately five (5) and approximately fourteen (14) years of age. The average height of a five-year old child is forty-four inches (44″). By the time the child reaches fourteen years of age he or she will have grown an additional twenty inches (20″) to an average height of sixty-four inches (64″). During these years of growing the child will need to be refitted for golf clubs every one and a half years. If a new set of golf clubs is bought every one and a half years, the expense will be great. If a longer set of golf clubs is not purchased, the child will compensate for the short golf clubs by developing an improper golf swing.
A golf club can be lengthened by removing the grip of the golf club, and then attaching an extender piece to the end of the golf shaft, and then re-gripping the golf club. This can be expensive and time consuming.
An example of an extension for a putter is described in U.S. Pat. No. 5,024,438 to Candow. The putter extension is used in order that the golfer may be at a more upright position when putting. The length of the putter is extended by removing the grip from the putter, placing a receiving sleeve within a cavity that extends longitudinally within the putter shaft, positioning an extension shaft into the receiving sleeve, and placing a grip over the extension shaft. The receiving sleeve is anchored into the putter shaft with an expansion joint. The disadvantage to this type of extension is that the process is both tedious and expensive. Furthermore, this type of extension device is used to extend the length of a putter but is not strong enough to withstand the stresses on a shaft of a driver or an iron resulting from the golf head impacting a golf ball.
Retractable golf clubs are known which allow a person to fold the golf club to a size such that it can be carried in a briefcase. However, this type of golf club is not adjustable to more than one playing length. This golf club is only adjustable to a second length for transporting purposes.
None of the above-mentioned prior art discloses a golf shaft for a golf club that can be adjusted to various playing lengths while being able to withstand stresses resulting from the golf club head impacting a golf ball.
Therefore, there is a need for an adjustable length golf shaft that is capable of handling these stresses and would allow a child to use the same set of golf clubs throughout his or her youth. Alternatively a rigid form grip, which may be repositioned on the shaft, will allow adjustment by the length of the grip.
It would also be an advantage if a golf putter was adjustable for length so the golfer could alter the length to suit their desired posture.
Telescoping golf shafts are described in patents, and the following patents represent the approaches to securing the shafts.
Middleton, U.S. Pat. No. 5,733,203, describes a telescoping putter, with 2 shafts, with a “locking screw” to secure the shaft.
Harrison, U.S. Pat. No. 5,649,870, describes a telescopic shaft arrangement where simple friction secures the two telescoping tapered shafts in a semi fixed position.
Mazzocco, U.S. Pat. No. 4,674,747 discloses a golf club having adjustable length shaft retractable between fully extended and collapsed positions. The golf club has plural concentric telescopic interlocking tubular sections which produce a friction lock between the tubular sections in a fully extended position. There is a club commercially available utilizing this principle (http://www.allinonegolfclub.com).
Sundin, U.S. Pat. No. 5,584,769, describes a shaft which can be constructed of two or more telescopically-adjustable or collapsible members to allow the same to adjust to different lengths for individual golfers. However, Sundin does not specify how the two shafts are to be secured in position.
Lee, U.S. Pat. No. 5,569,096, describes “the shaft inserted into the handle, threadably tightening a locking nut over a flexible ring and a external thread until the flexible ring is squeezed over the shaft prevents the shaft from slipping—thereby effectively locking the shaft in the desired length.”
Acculength Golf, www.acculength.com, markets a range of children's golf clubs which use introduced spacers to add length, but the device is not reversible, limited to 5 inches of adjustment, stepwise only, and do not conform with the Rules of Golf for play.
The leading company in specialist children's clubs is US Kids Golf, www.uskidsgolf.com, but this company only has a number of non adjustable length club sets available for children with in a specified height range.
Napolitano, U.S. Pat. No. 5,282,619, describes a shaft which has a number of telescopic sections where a locking nut and a compression ring permit adjacent sections of the telescopic section to be locked in a fixed position relative to each.
Heath et al, U.S. Pat. No. 5,496,029, describes an adjustable golf shaft for a golf club which allows a child to use the same set of golf clubs during childhood and into his or her teen years. This invention uses a compression fitting that can be loosened, the second shaft member can be expanded outward from the first shaft member lengthening the golf shaft, and the compression fitting can be tightened fixing the first shaft member relative to the second shaft member.
U.S. Pat. No. 7,074,135, (to Moore) described:                “An adjustable length golf putter, including at least one shaft, at least one grip attached to the at least one shaft, a self-locking mechanism associated with the putter for lengthwise adjustment of the at least one shaft relative to the at least one grip, the mechanism configured for accommodating an adjustment tool, and being locked by default so that the tool must be engaged in the mechanism for the lengthwise adjustment.”        
The Rules of Golf do not allow readily made adjustment to clubs, and until May 2002 an adjustable length putter has never been determined as legal by the United States Golf Association.
Puku Ltd, a company in which the applicant is a shareholder, is in receipt of a letter from the United States Golf Association™, which states “the default-locked mechanism submitted has been judged conforming with the Rules of Golf.” (letter from the United States Golf Association, April 2002, Decision 2002-185).
This is the first time ever that a length adjustable putter (U.S. Pat. No. 7,074,135) has been approved. The United States Golf Association™ has decided the default locked mechanism submitted can not be inadvertently or secretly adjusted by the golfer during the play of a round of golf.
However none of the above patented inventions or marketed products have addressed how to create an adjustable length club mechanism for putters, but also applicable to clubs other than the putter, which exhibit all the following characteristics:    1. Simple in operation,    2. Economic to manufacture,    3. Offering a variety of length adjustments, continuous or step-wise.    4. Offering reversible length wise adjustments, where a lengthened club can be subsequently shortened, and vice versa.    5. Strong enough to be safe in use, where the swing speed and subsequent mechanical forces are considerable greater than present when using a putter.    6. Strong enough to meet the requirements of the governing bodies of golf (United States Golf Association, USGA, and the Royal and Ancient Golf Club of St. Andrews, R&A)    7. Where the adjustment requires using a specialist tool to operate, also to meet the requirements of the USGA and R&A.
Evidence of the difficulty in meeting the above requirements, other than there being no patents describing how to do so, is that there are no clubs on the market adjustable in length in a continuous or step wise manner.
Other than the afore-mentioned children's brands there are no adjustable length clubs available other than putters. Ping Golf, www.ping.com a leading brand which champions custom fitting of golf clubs to the individual does not have adjustable length clubs, even putters. Neither do www.thomasgolf.com and www.henry-griffitts.com two other brands who claim to specialise in fitting the club to the individual.
To date the USGA and R&A have not sanctioned an adjustable length club other than putters, of which the Moore Puku™ putter is believed to have been the first. It is advantageous to be able to customise the length for all types of golf clubs, to suit the golfer's physique, and preferred posture when playing.
An example of clever use of helices is the well known children's toy, commonly known as the “Chinese Finger Pull” where a helically woven tube (originally bamboo) frictionally locks on each finger inserted into opposite ends of the device. For the purposes of this patent this device may be described as a contra-rotation multiple helix mechanism, or a “Chinese finger helix mechanism (CF_Hx).
A Chinese finger pull device uses the principle that a helical form will reduce in internal and external diameter when a lengthening force is applied. So in the case of a Chinese finger pull the inserted fingers initially slightly expands the device, and creates an initial friction engagement of the fingers to the internal surface of the device. When the fingers are pulled apart the device lengthens and the internal diameter reduces increasing the friction, which means the harder the fingers are pulled the more they are trapped. The solution is not obvious initially but it is to shorten the finger pull thereby increasing the internal bore and allowing the fingers to be removed.
A disadvantage with the Chinese finger pull device (as a connection mechanism) is that generally another person is required to hold the device in a compressed state to enable the fingers to be withdrawn.
An adjustable mechanism for use in adjustment of at least two shafts is disclosed in WO2007/086759 (to Moore). This adjustable mechanism includes a spring attached to a first shaft, the spring having an outer diameter of similar dimension to the internal diameter of a hollow second shaft to which it may be connected in an adjustable manner. The mechanism utilises the fact that the outer diameter of an extended spring is less than the outer diameter of the spring when unextended. Thus by applying a force to extend the spring the outer diameter of the spring can be reduced allowing the spring and first shaft to be moved through the second shaft into a desired position. When the force is removed the spring is biased to return to its unextended form, thus causing the outer surface of the spring to bear against the internal surface of the second shaft to produce a friction fit.
The force required to extend the spring may be provided by a tool which can be engaged with the spring to pull it or rotate it to wind it up (or a combination of both actions), which can reduce the outer diameter of the spring.
This adjustment mechanism, once engaged, can effectively resist a force applied to pull the two shafts apart (due to the friction fit), or to rotate the first shaft relative to the second shaft in the same direction as the winding of the spring (clockwise or anticlockwise) as this action attempts to increase the outer diameter of the spring thus increasing the friction fit.
However, a problem with this type of adjustable mechanism is that the friction fit can be loosened by rotating the first shaft relative to the second shaft in the counter direction to the winding of the spring and pulling the two shafts apart, as this combined action reduces the outer diameter of the spring and therefore reduces the friction fit.
A problem encountered in testing the concepts in this invention is that all parts have manufacturing variability and tolerances. Therefore perfect alignment is almost impossible to attain, and a rattle or vibration can occur between the telescopic elements are together, and it would advantageous if a detail compensated for and reduced the rattle.
Tubular elements are common in industrial and consumer applications, and other than golf there are many situations which would benefit from a relatively simple, strong, reliable, and affordable mechanism which allows connection, possibly telescopic, between two elements. Some examples are pipe work, plumbing, oars and paddles, the frames of a horse racing sulky, and furniture.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.